In an image monitoring device or system, a technique to track a moving object (e.g., a vehicle or a moving animal) is important. The image monitoring device can be used in an unmanned aerial vehicle (UAV).
In the field of image tracking technology, an optical flow method is commonly used in tracking images to moving objects. Lucas Kanade pyramid (“LKP”) is an accepted optical flow method often used in a moving object tracking apparatus. The LKP method is divided into two key steps. In the first step, feature points are extracted as tracking objects. In a second step, target positions of selected feature points are obtained by an iterative process according to the selected feature points. Although the LKP method can accurately obtain the target positions, the LKP method must filter severely deviated target positions during the tracking process to avoid errors to subsequent iterative tracking processes.
The Ransac method, forward and backward tracking error method, or normalization correlation coefficient of image block can be used to filter the feature points. However, these methods require large computations. Thus, a moving object tracking system using the above methods has a relatively low arithmetic speed, and accordingly, the unmanned aerial vehicle using the above moving object tracking system has a low tracking efficiency.